Tile setter



Feb. 20, 1968 B. CUMMINGS Original Filed Jan. 22, 1952 ATTORNEYS UnitedStates Patent 26,345 TILE SE'ITER Howard B. Cummings, New Castle, Pa.,assignor, by mesne assignments, to Shenango Ceramics, Inc., New Castle,Pa., a corporation of Delaware Original No. 3,181,223, dated May 4,1965, Ser. No. 170,530, Jan. 22, 1962. Application for reissue May 1,1967, Ser. No. 641,731

11 Claims. (Cl. 264-58) Matter enclosed in heavy brackets [II appears inthe original patent but forms no part of this reissue specification;matter printed in italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE Setter and method for keeping flat tilestraight and free of sailing during firing of glaze by supporting tileon cantilever supported apposed sets of shelves whose outer edgesprovide parallel horizontal bearing surfaces so that a tendency ofunsupported tiles to sag in the center during fire is counterbalanced byoverhanging margins of the tiles. Under surfaces of shelves are slopedso that accumulations of volatilizcd glaze not ventilated away orcarried out by condensation on undersides of tiles stacked in the setterwill run to the sides and not drop on tiles. Edges of shelves are butslightly raised above upper shelf surfaces which thus act as limits forthe sagging of the tile margins during fire.

This invention relates to improvements in kiln furniture for the firingof the tile and, more particularly, to setters for the firing of glazedflat ceramic tiles for walls, floor ing, or the like.

At the stage of manufacture of ceramic tiles at which setters madeaccording to this invention are employed, the tile is usually in thecondition of green ware comprising a body of dry unfired clay ofrelatively thin cross-section and conventional polygonal shape (usuallysquare or otherwise rectangular). The relatively smoother upper surfaceof the clay body carries a dried coating of frit in which are thenecessary fluxes, opacifiers, and colors to be fused into an adherentsurface glaze when the clay body is fired to the semi-vitreous conditionof the manufactured tile.

With the green tile prepared for firing as described above, it hasheretofore been the preferred practice in the art to support the tile inshallow scttcr trays of a suitable refractory material. These trays haveflat, imperforate bottoms and sides extending above the tile-supportingsurface of the bottom a distance sufficient to provide clearance betweenthe glazed surface of a tile placed in one tray and the underside of atray above it. With one or more tiles (depending upon the size of thetiles and trays) placed in each tray, a number of trays are stacked intoa hung with a cover plate over the top tray of the bung. The traysmaking up a bung are usually cemented together at the parting linebetween the sides of one tray and the bottom of the tray above toprevent the shifting of the trays with respect to each other as thebungs are loaded on the cars on which the bungs are conveyed in and outof the kiln for firing. The sides of the trays are provided withopenings to permit the movement of gases in and out of the trays, butthe size of the openings must be relatively limited to provide thenecessary; strength for supporting other trays in the bung as well asthe bungs which may be loaded on top of the bottom bungs when loading akiln car. The function of the flat bottom of the trays in a bung is toprovide a fiat supporting surface upon which each tile will rest so thatthe tile will not warp as it is brought to its ice maximum firingtemperature; also, the bottom of one tray (plus the cover plate in abung) serves to shield from dirt and contamination the molten glazewhich fuses together and to the body of the tile as it is being fired.After the tile is fired and the bungs coo ed, the trays are removed,broken apart to remove the tile, and then reused.

A problem of the above-described tray-style of setter is that inrepeated usage, the trays themselves tend to warp so that the "trayswill not support and produce straight tile, in which case, they must bediscarded. The tray setters are also subject to considerable crackingand breakage in the stacking, breaking apart, and other handling of thetrays making up the bungs. Still another fault of the above-describedtray setters is that, in repeatcd re-use, glaze will volatilize andcondense on the underside of the tray above it. In time, thisvolatilizcd glaze may accumulate to the point Where, at the maximumfiring temperature, it drops onto the file below it or, in reaching thistemperature and because the rate of thermal expansion of the glaze isdifferent from that of the refractory from which the trays are made, theaccumulated glaze spalls off the underside of the tray and falls ontothe glaze of the tile beneath; in either case, the tile is spoiled andmust be discarded. Also, a considerable amount of labor is involved incementing up the bungs and, because the so cemented bungs are seldom ofprecisely equal height, time-consuming care must be used in loadinglayers of bungs upon another to provide a stable load in the kiln cars.

In addition to the above faults and expenses of the system of firingtile in setter trays which have heretofore been considered inherent andunavoidable, a less ap preciated but nonetheless serious element of costis that the trays themselves are more massive than the mass of the tilebeing produced in order to provide the required strength and stabilityof the bungs. As a consequence, a major portion of the heat produced ina tile kiln, as well as its volumetric capacity is taken up by thesetters, rather than by the tiles to be fired.

It is the object of this invention to provide a setter for firing tilewhich not only produces straight tile but eliminates many of the abovefaults and disadvantages of the tray setters as above described. Thatis, the cost, weight, and mass of refractory material per tile beingfired are greatly reduced and the capacity of a kiln greatly increased,both volumetrically in that a greater number of tiles may be carried bya kiln car (and in the rate of production in that the tiles may be firedfaster because less time is required to bring a lesser mass ofrefractory material up to temperature). Also, the labor involved incementing the trays into a hung is eliminated and the care and timerequired in loading the kiln cars or other conveyor means is minimized.

A still further advantage is that, due to improvement of ventilation ofthe tiles as fired, more uniform color can be developed among the tilesof a lot being fired and a better color match may be obtained betweentiles fired in different lots. And, due to the configuration of the tilesupports, the spoilage of glaze from accumulations of volatilizcd glazeon the setter is substantially eliminated.

Other and further objects and advantages of this invention will beapparent from the following specification, claims, and drawings, inwhich:

FIG. 1 is a front elevational view of a two-cell tile setter madeaccording to this invention.

FIG. 2 is a fragmentary side elevation of the setter shown in FIG. 1,showing in phantom the location of a tile supported on the uppermost ofan opposed pair of cantilever shelves.

FIG. 3 is a detailed elevation taken from FIG. 1 and showing in phantomthe location and support of tiles on the cantilevers.

As shown in FIGS. 1 and 2, a tile setter made according to thisinvention comprises a box having a pair of side walls 11 supporting abottom 12 and top 13, leaving an open front and back. To minimize themass of the refractory material making up the setter 10 withoutappreciably reducing the strength and stillness of them, the side walls11 are provided with suitable vertically extending recesses 14 and thebottom 12 and the top 13 are provided with horizontally extendingrecesses 15 and 16, respectively. Depending upon the size of the tile tobe fired, the modular dimensions of the setter with respect to thedimensions of the kiln car or conveyor on which it is to be placed, andthe weight of the setter, when loaded with tile, that is convenient tohandle, the top, bottom, and sides of the setter may define a singleopenended cell or a plurality of cells. In this particular embodimentshown, the setter is divided into two cells by a vertical partition 17.

In each cell the sides thereof are provided with a plurality of opposedhorizontal cantilever shelves 18 extending inwardly toward each otherand slightly upwardly from the side walls with which they are integral.Referring to FIG 3, the side Wall 10 and partition 17 are spaced fromeach other a horizontal distance sufiicient to permit a green tile, withthe unfired glaze uppermost, to be inserted into the cell withsufficient clearance to permit easy loading and unloading of a tile ontothe opposed shelves. Each shelf 18 extends into the cell a distancesufficient to locate its outer and uppermost edge in a position tosupport a tile along a line midway between the center and the adjacentedge of the tile. It is to be noted that each shelf is slightly thickerat its root where it is integral with a side wall or partition than itis at its outer end, and that the angle (a) at which the underside of ashelf extends with respect to its supporting wall is slightly greaterthan the angle (b) at which the upper surface extends. This is toprovide structural strength with a minimum of mass of refractory whilepresenting the upper edge of the shelf as a line of support. It is alsoto be noted that the opposed pair of shelves are spaced from each othera distance to provide a spacing between tiles supported thereon at leasttwice the thicl ness of the tiles.

The bottom 10 is provided with horizontal ridges 19 which afiordtile-supporting lines parallel to and vertically aligned with the linesof support provided by the outer upper edges of the shelves 18. Thebearing surfaces of the top and bottom as defined by the recesses 15 and16 are preferably parallel and provide an over-all height equal to theheight of other setters to be loaded as a layer on a kiln car.

With the setter loaded with tiles as indicated in FIG. 3, it is placedwith similar setters on a kiln car or conveyor and the tiles are thenfired. In essence, the operation and advantage of this invention flowfrom a utilization of the discovery that, contrary to prior practicewith tray setters and the like, it is not necessary to support a tilehaving a typical clay body and thickness during its fire throughout theentire undersurface or substantially so. Rather, the tile will remainstraight if it is simply supported along a line approximately midwaybetween its edge and center so that the Weight of the portion of tilewhich overhangs one side of the line of support will approximatelybalance the weight of the portion which overhangs the other side of theline of support, as shown in FIG. 3.

By the above construction, a substantial portion of the mass ofrefractory material heretofore taken up by the bottom of tray setters iseliminated and a setter made according to this invention is equivalentto a hung of tray setters, but of substantially less height than a hungcarry ing an equal number of tiles. At the same time, the glaze on thetiles is shielded by the tile above it, rather than by the bottom of asuperimposed tray in a hung of tray setters. There is less build-up ofvolatilized glaze to cause spoilage by dropping or spoiling because muchof the glaze volatilized from the surface of one tile will deposit onthe underside of the shielding tile above it and, thereby, be removedwhen the tiles are fired and removed from the setter. Also, due to thegreater ventilation permitted by the open ends of the setter, muchvolatilized glaze that might accumulate in conventional setters may beexhausted out of the setters by the flow of gases through the setters.Another advantage of the greater ventilation is that the glaze isbrought to fusion and colors are oxidized more evenly throughout themass of tile being fired, producing more uniform color between tiles ofa lot being fired and permitting a better duplication of conditions sothat the colors of different lots can be more evenly matched.

It is also apparent from this construction that no labor is lost incementing setter trays together and, because all setters may be of equalheight, one layer of setters in a kiln car will provide a level, stablesurface for a succeeding layer, enabling cars to be loaded more quickly.

This invention is not to be considered limited to the specificillustrative embodiment disclosed but may be modified to meet therequirements of specific tiles, kilns, and loading techniques andrequirements. Accordingly, those skilled in the art may vary thisinvention within the scope of the appended claims without departing fromthe spirit and purpose thereof.

What is claimed is:

1. A tile setter for firing ceramic tile comprised of opposed side wallsjoined at their top and bottom to define a cell, a plurality ofcantilever shelves carried by each side wall, said shelves beinginclined upwardly with respect to the wall supporting them, and shelvescarried by said opposite walls being arranged in pairs to provide pairsof tile supporting edges, the two edges in any one pair beingequidistant from the bottoms of the supporting walls and one edge insuch pair being spaced from its supporting side wall a distance equal tothe distance the other edge in the pair is spaced from its supportingside wall, whereby, when a tile is supported on a pair of said edges,the weight of tile between said edges is substantially counter-balancedby the weight of the portion of said tile extending beyond said edgestoward the sup porting side walls.

2. A tile setter as defined in claim 1 in which said side walls arespaced from each other a distance to provide clearance for a tile to besupported on the said pairs of shelves and the shelves of said pairsextend toward each other to support said tile on their respectivetile-supporting edges providing lines of support located substantiallymidway between the center of a tile and the edges of said tile adjacentsaid walls.

3. A tile setter as defined in claim 2 including a bottom member joiningadjacent side walls, and a pair of ridges on said bottom member spacedfrom each other and the side walls as the supporting edges of a pair ofshelves are spaced from each other and the side walls.

4. A tile setter as defined in claim 2 which is open at the front andback to permit ventilation of said cell and insertion of tiles into saidcell for support on the tilesupporting edges of pairs of said shelves.

5. A tile setter comprising a plurality of cells as defined in claim 1and joined together by tneans of a common side wall between cells.

6. A multi-cell tile setter comprising a top member, a bottom member,side walls, and at least one vertical partition forming a cell, asdefined in claim 1, between said partition and said side Wall.

7. The met/10c! of firing flat green file to minimize .ragging duringfire comprising the steps 0] providing a refractory setter with opposedvertical side walls and at least one open side, said side walls beingspaced internally from each other a distance greater than the lt'io'f/lof {/16 tile to be fired therein, each of said side walls carrying aninternal shelf extending toward an internal shelf carried by the opposedside wall to provide a pair of adjacent substantially parallel andhorizontal shelf edges functioning as narrow bearing surfaces for a tileto be fired thereon and said edges being above the upper horizontalsurface of their respective shelves and spaced apart a distance equal tosubstantially one-half the width of tile to be fired in said setter,placing a green flat tile on said edges so that substantially equalmargins are supported above each of the shelves in the pair and firingsaid assembled setter and tile, maintaining said shelf edgessubstantially horizontal during firing so that the margins of said tilesubstantially counterbalance the center portions supported between saidedges.

8. The method as defined in claim 7 including, in the step of providinga setter as defined therein, providing a setter with a plurality of setsof said shelves, the said edges of which are spaced vertically withrespect to each other a distance at least twice the thickness of saidtiles and in which tiles placed on said shelves are coated on theirupper surface with unfit-ed glaze but are substantially free of glaze ontheir undersurfaces, whereby the underside of a tile stacked in spacedarrangement on a set of said shelves and supported between said edgesabove another tile serves as a receptor of at least some of the glazevolatilized during the step of firing.

9. The method as defined in claim 8, including in the step of providinga setter as defined therein, a setter in which the undersurfaces of saidshelves slope upwardly toward its inner edge from a point on itssupporting wall sufficient to provide clearance from a tile supportedbeneath said shelves, whereby glaze which volatilizes from said tilesduring firing and condenses on the undersides of said shelves will tendto run toward said walls rather than drop on a tile beneath.

10. The method as defined in claim 9, including, in the step ofproviding a setter as defined therein, providing a settter in which theupper surface of said shelves, in their areas intended to be overhung bysaid tiles, are at no point vertically above their respective edges butare closely adjacent the planes defined by the respective opposed andparallel horizontal edges, whereby the upper surfaces of said shelvesserve as limits for the sagging of the margins of said tiles during thestep of firing.

11. The method as defined in claim 10, including, in the step ofproviding a setter therein, providing a setter with opposed open sides,and ventilating through said open sides during the step of firing.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

UNITED STATES PATENTS 1,848,200 3/1932 Robinson 25153 1,860,374 5/1932Vincent 25153 1,885,691 11/1932 Drcssler 25153 2,567,609 9/1951 Lovatt25153 2,602,984 7/ 1952 Owen 25-153 OTHER REFERENCES G. Klein:Experience With Open Setting of Glost Wall Tile in Funnel Kilns, inJour. Amer. Ccr. Soc. 38(5), pp. 403-412, May 1931 (pages 406-407 reliedupon), TP 785 A 62.

WILLIAM J. STEPHENSON, Primary Examiner.

